private void resolve(Vector n)
{
// this is the tangent vector at the rim particle
tan = new Vector(-rp.curr.Y, rp.curr.X);
// normalize so we can scale by the rotational speed
tan = tan.normalize();
// velocity of the wheel's surface
Vector wheelSurfaceVelocity = tan * rp.Speed;
// the velocity of the wheel's surface relative to the ground
this.Velocity += wheelSurfaceVelocity;
Vector combinedVelocity = this.Velocity;
// the wheel's comb velocity projected onto the contact normal
float cp = combinedVelocity.Cross(n);
// set the wheel's spinspeed to track the ground
tan *= cp;
rp.prev = rp.curr - tan;
// some of the wheel's torque is removed and converted into linear displacement
float slipSpeed = (1 - _traction) * rp.Speed;
normSlip = new Vector(slipSpeed * n.Y, slipSpeed * n.X);
curr += normSlip;
rp.Speed = rp.Speed * _traction;
}
